Apple has released iOS 4.3.4 (iOS 4.2.9 for users on Verizon) which fixes a vulnerability with the operating system’s PDF support that could enable attacks via maliciously-crafted PDF files. Earlier this month, Jailbreakme.com relaunched using this PDF exploit to enable user to jailbreak their iOS devices. As expected, the patch shuts down that particular jailbreaking technique.

The update is free for the iPhone (3GS or newer), iPad, and iPod touch (third and fourth generations).

The PDF exploit was also the subject of a consumer alert issued by Germany’s Federal Office for Information Security warning users of iOS devices to stay clear of PDF files from unknown senders. Although there are no known cases of the PDF exploit being used maliciously in the wild, security experts warned the technique could quickly be exploited for malicious purposes.